Rotary devices are widely used in the construction of machinery to permit the selective rotation of a workpiece, such as a component or a tool and the like. In automated fabrication and assembly devices, for example, some end effectors are constructed to have an extensible gripping member supported by a rotary positioner so that a gripped workpiece can be rotated in order to place it at different possible rotational orientations.
Generally, such a rotary positioner typically has a fixed structure and a rotating structure. Often times it is necessary to traverse the interface between the fixed and rotating structures with hardware that supplies a utility to the rotating structure, such as in communicating electrical energy or in supplying fluidic energy to the rotating structure.
As for electrical utilities, some previously attempted solutions employ a slip ring to construct a rotating electrical connector. However, a slip ring requires a continuous contacting engagement between circuit terminals and a rotating part, which disadvantageously presents wear and tear issues and particulate contamination issues. Also, slip rings do not provide a hard-wired solution for applications where controlling electrostatic discharge is a requirement.
As for fluidic utilities, some previously attempted solutions employ a rotary union to construct a rotating fluidic connector. However, a rotary union is inherently not well suited for miniaturization; even a rotary union for a small workpiece application is disadvantageously big, bulky, and cumbersome to incorporate into an automated system. Furthermore, the stiction created by the moving seals in a rotary union creates problematic torque and position control issues.
These individual disadvantages associated with using a slip ring or a rotary union are compounded in a system that requires both electrical and fluidic utilities be provided to the rotating structure, meaning that both a slip ring and a rotary union are employed. Improvements are needed in the manner of passing power utilities to the rotating structure of a rotary positioner to resolve these disadvantages associated with the previously attempted solutions. It is to those improvements that the embodiments of the present invention are directed.